let f be the function f(x)=x(x+2)

Find and simplify f(x)-f(-x)/2x

I tried pluggin in whatever is for x in the first equation and get an answer for each value but it isn't working out can someone please help thank you

f(x) =x(x+2)

f(-x) = (-x)(-x+2)

f(x)-f(-x) = x(x+2)- (-x)(-x+2)
= x(x+2) + x(-x+2)
= x(x+2-x+2)
= x(4)
= 4x